In commonly owned U.S. Pat. No. 3,680,344 there has been disclosed a rectangular basin or soaking pit in which several parallel beams are disposed below the liquid level and are formed with upstanding stakes or rack teeth defining between them the soaking compartments or bays in which the slabs can be deposited on the underlying beams. A railborne transport mechanism comprises a pair of transporters or cranes each including a bridge or traverse spanning the pit, the cranes being provided with hoists for lowering a billet into a bay and extracting it therefrom after cooling. Each hoist comprises a slab holder in the form of a bracket, suspended from a pulley block, that embraces the slab between two vertical walls and is provided at its bottom with an upwardly retractable latch member on which the slab rests before being deposited on the beams of the pit.
In another commonly owned U.S. Pat. No. 3,895,498, a double slab gripper has been described in which two downwardly open pockets can be simultaneously aligned with adjacent soaking compartments in order to enable a hot slab, carried in one of the pockets, to be lowered into one of these compartments whereupon a previously cooled slab, entering the other pocket during the lowering operation, can be extracted from the adjoining compartment. The pockets can be alternately closed at the bottom with the aid of one or more retractable latch members.
While these prior systems operate generally satisfactorily, their hoisting mechanisms are relatively bulky inasmuch as three vertical wall members are required therein to form the two slab-receiving pockets. The hoist drive, accordingly, must be capable of lifting the weight of the heavy gripper structure in addition to that of the engaged slab or slabs.